Electric utilities represent the largest energy provider to consumers at the industrial, commercial and residential levels. The infrastructure to support the delivery of energy to the 131 million customers in the U.S. has been evolving over 100 years to what it is today. During this time, the distribution voltage level has become standardized at 69 kV, 34.5 kV, 17.2 kV, 12 kV, 7.2 kV, 4.7 kV, and 2.7 kV. These voltages are transformed to 480, 240, and 120 volts for use in machinery, systems, and homes.
The electrical distribution network can be compared to UPS van delivery service. UPS vans do not manufacture the products they deliver, nor do they carry them cross country. A UPS van is used to distribute packages at a local level.
The electrical distribution system or network connects to the electrical transmission system to deliver energy to the end-user. The transmission system connects to the generation system where electric energy is produced. Together, these three systems instantly deliver energy to all customers on demand. However, if the demand becomes too great or if the distribution system breaks down, there is no alternative way to deliver energy to end-users and a blackout or outage occurs.
The distribution system is different than the transmission system. The transmission system is easily noticed along highways and in the countryside. It includes imposing structures, long cross-country transmission lines, and power plants. Conversely, the distribution system is part of the urban landscape.
The distribution system or network is made up of 20- to 40-foot wooden or steel poles from which are suspended power lines or conductors, disconnect devices, lightning arrestors, capacitors, insulators, and a variety of pole line hardware elements, each of which plays a crucial role in keeping the lights on and factories running. This uptime of the electrical system or network is defined by one word: reliability.
The distribution system connects to the electric utility at a substation where transmission voltages are reduced to distribution levels. One transmission circuit delivers energy over many distribution circuits. A substation is like a UPS freight terminal where large cross-country trucks break down their loads to be picked up and delivered by smaller UPS vans. Power lines supported by power poles are referred to as overhead lines.
Due to deregulation in the 1990's, which segregated power generation from the distribution of electricity, maintenance of electric distribution systems is no longer fully included in a utility's rate base. This has resulted in a 50% reduction in electric distribution maintenance spending since 1990.
Electric utilities are largely regulated by state and federal entities that monitor pricing, consumer satisfaction, and reliability. The state PUCs are tasked with the regulation of pricing and customer reviews of the electric utility as a monopolistic supplier of energy. The PUC has the right and ability to deny a utility the right to increase the charge for energy to a class of customers based upon public hearings and customer review. A recent rate hike for a major power company was denied in April of 2006 because according to the PUC of Ohio (PUCO) there was a “failure to maintain baseline performance levels of 75% of its distribution circuits.” Baseline performance can be interpreted as keeping the lights on enough of the time to avoid customer complaints to the state PUC.
There are over three million miles of overhead and underground electrical distribution circuits in the U.S. that provide consumers access to electrical energy. Ninety percent of all interruptions to electrical service occur when elements of the distribution system break down.
In this report, particular attention is paid to the electrical distribution network as an aging infrastructure that is being continuously strained without the appropriate level of attention and rehabilitation. See: www.energetics.com/gridworks/grid.html, Department of Energy.
Decisions made by Public Utility Commissions (PUC) on the price a utility can charge for energy are often affected by the costs that consumers must bear for unreliable service. A study by the Department of Energy (DOE) in 2004 found that there is an annual $79 billion cost to consumers resulting from power outages.
Thirty-nine states have some form of punitive rate impact based upon customer satisfaction and the number of outages within a utilities service territory. These states each have mandatory outage reporting requirements and reliability measurement targets.
Some power failures like those due to natural disasters are unavoidable, but avoidable outages from failure of circuit elements or components make up 31% of all outages as measured by the National Energy Regulatory Commission (NERC).
In 2003, there were $2.4 billion in electric rate cases pending with PUC's. A rate case deferral or reduction of 54% or $1.3 billion was levied based upon service reliability and customer satisfaction issues.
Electric utilities in the U.S. experience an estimated 6 million outages each year related to electric distribution mechanical failures. This has resulted in a loss of $750 million annually to the utilities, in addition to failures to receive rate increases due to unsatisfactory reliability performance amounting to as much as $1.3 billion in 2003.
Thus, the electric utilities are dealing with the conflicting goals of delivering strong financial performance for investors while providing increasingly higher reliability performance for state utility regulators.
The distribution system is the delivery point for all utility customers, except the largest industrial customers such as steel mills and automotive manufacturing plants. Large industrial customers purchase energy on a wholesale basis at transmission voltage levels of 138 kV, 230 kV, 345 kV, 500 kV, or 765 kV. These wholesale customers include other utilities that buy and sell power on the wholesale market.
Power is the instantaneous measure of energy. Energy is power consumed over time and this is what small customers, like homes, purchase. Power is measured in thousands of watts or kilowatts (kW). Energy is how much power is used over time and is measured in thousands of watts per hour of use, or kilowatt-hours (kWh). At home we pay for energy by the kWh which averages about 10 cents per kWh. A typical home load may consume 1,000 kWh per month or about $100 of energy.
If a failure occurs in the distribution system, a customer looses electrical service. At the same time, the utility is impacted in several ways. First, it cannot sell energy to its customers. Second, customers immediately complain to the utility and the utility must react to these complaints. The utility must staff complaint lines, pay overtime to repair crews, locate problems and dispatch crews to the trouble area, purchase unplanned circuit elements to replace those that have failed, and explain to the Federal Energy Regulatory Commission (FERC) and the PUC why the problem occurred, what it is doing to avoid the problem reoccurring, and try to regain its customers' confidence through public relations and advertising.
A power outage or history of unreliable service also raises the issue of competition. In most states, electric customers have the opportunity to select who will provide them their energy. This has come about as part of the Energy Deregulation Act. This has set up fierce competition between the largest Investor-Owned Utilities (IOUs) like AEP, Con Ed and Duke Energy and 100 others; federal utilities including the Bonneville Power Administration (BPA), the Tennessee Valley Authority (TVA), and the Western Area Power Administration (WAPA); the Rural Electric Cooperatives (COOP) of which there are over 2,000; and the Municipal Electric Companies like the City of Columbus in Columbus, Ohio, of which there are thousands. Each of these entities must maintain customer loyalties or risk customer migration.
The distribution circuit or system is supported by a number of hardware elements. These elements maintain proper operation when they are all working. Age, vibration, weather, air pollution, lightning, and load all work against these elements causing them to loosen, crack, and fail. As these elements or components begin to fail, they emit high-frequency signals (EMI). These signals become pronounced as the element nears catastrophic failure or flashover. The result of a failure is an outage on the circuit feeding thousands of customers.
When an energized component fails, there is a telltale emission that results from electrical energy escaping from the circuit. This is much like a radio antenna, broadcasting the imminent failure. Devices have been designed that can report these emissions to expensive computer-based communication networks. The basic signature of failures is an arc which evidences an R.F. output exhibiting a very steep rise time followed by a decay. Important energy involved is one evoked from the rise time and not the decay. Looking to some component failures, with a broken distribution insulator, the electrical field surrounding the insulator begins to leak through the broken areas of it and sharp edges of the fracture emit these (EMI) signals that are detectable. The broken device becomes critical with a flashover of the insulator and an outage of the associated distribution circuit. Conductor brackets are designed to hold an energized conductor in place and maintain proper spacing from all other elements of the distribution system. If such a bracket fails, the conductor becomes loose and could swing into nearby structures of vegetation. If the conductor contacts any structure, tree or other path to ground, an outage occurs. Freeze-thaw cycles of weather may be a culprit in the causation of a loose conductor bracket. Conductors themselves may be partially broken from overload or other mechanical damage. The broken strands of the conductor limit the loads that can be supported before the conductor fails electrically. These strands may also serve as small antenna which emits specific signals.
The distribution circuit or system is a single path for the delivery of energy to homes, businesses, and industry. It begins at the step-down transformer at a substation. The step-down transformer reduces the voltage of the circuit from transmission levels to lower distribution voltages. An involved conductor or conductors in the entire network is energized to the distribution voltage level until the distribution transformer reduces the voltage once more to the appropriate low delivery voltage. A home usually receives a voltage of 120 volts line to neutral or 240 volts line to line.
If any of the hardware connecting, insulating, or protecting the distribution circuit or system fails, all of the loads downstream of the failure become affected. Sometimes a power outage occurs because there has been a problem such as a tree limb falling across a line or an animal causing an electrical fault by bridging across two conductors. However, equipment or component failure is the leading cause of circuit failure. When an equipment or component failure occurs, the broken element must be located and replaced.
Power failure can be a nuisance to the homeowner. Who hasn't had to reset their digital clocks following a power outage? But long-duration outages—those outages resulting from equipment failures—can cause serious damage particularly to a business which relies on electricity to operate.
A national survey of 411 small-business operators conducted in January 2004 by Decision Analysts for Emerson raises big questions about the ability of small companies to withstand a lengthy power outage. The survey, which is accurate to plus or minus five percentage points, found that 80% of small businesses experienced an electrical porter outage in 2003. Further is was determined that 60% have no type of back-up power supply. Also, a Small Business Power Poll found that 75% of U.S. small businesses rate electrical power outages as only marginally less of a threat than competition (79%) and trauma from computer failure and a fire (77%). See:    Eckberg, John, “Power failures: Small companies, big losses,” The Cincinnati Enquirer, Mar. 14, 2004.
Weather plays a significant role in electrical distribution equipment failure. When weather is inclement, a power outage is more than a nuisance. In this regard, many Canadian home-heating systems depend on electric power. Power lines and equipment can be damaged by freezing rain, select storms, high winds, etc. This damage can result in supply interruptions lasting from a few hours to several days. An extended power failure during winter months and subsequent loss of heat can result in cold, damp homes, severe living conditions, and damage to walls, floors and plumbing.
Litigation resulting from power failures is often a secondary effect. So much of the safety infrastructure on roadways, emergency alert systems, and life-support systems are dependent upon reliable energy.
Systems exist that address the concept of predictive circuit review, but these systems require the problems to become so bad that they are casually observed by customers. These are ultraviolet (UV) and infrared (IR) imagery of the circuit elements. UV cameras, such as those manufactured by OFIL of Israel, and IR cameras manufactured by FLIR, Inc., are available.
Existing monitoring products have a relatively high base cost and require technical skills, devoted labor, and post-analysis to be effective. The effectiveness of these methods relies on the opportunistic discovery of an already failing circuit element. There is no discovery survey associated with their use.